Hello all, great to find a site such as this dedicated to vintage wooden propellers! At the moment however I am trying to identify some metal propellers, probably from the 30's, by Hamilton Standard and Hartzell. Does anyone know of a similar resource to this site for metal propellers?

Have you tried contacting the manufacturers themselves? With metal props, the lifespan is such that they can remain serviceable for a longer time, so the manufacturers may be more compelled to keep the data accessible. Many of the wooden props simply became obsolete, and the manufacturers probably never envisioned that they would some day be "collectible".